1. Field of the Invention
The present invention relates to a method of fixing a flexible boot made of a resinous material to a counterpart, for example, a constant velocity universal joint, used in association with a drive shaft of an automotive vehicle and in various industrial machines and equipments.
2. Description of the Related Art
As is well known to those skilled in the art, the constant velocity universal joint employed in, for example, an automotive vehicle has a tubular flexible boot made of a resinous material or synthetic resin employed therein for the purpose of preventing foreign matter such as, for example, dusts from intruding into the constant velocity universal joint and/or preventing a grease, filled inside the constant velocity universal joint, from leaking therefrom to the outside. Fixture of the tubular boot to the constant velocity universal joint is generally carried out by mounting the flexible boot on the constant velocity universal joint with annular anchoring portions thereof at its opposite ends encircling an outer ring and an inner ring axle, respectively, and firmly fastening a flexible metal hoop exteriorly around each of the annular anchoring portion of the boot.
In order to secure a sufficient sealability required at each of the annular anchoring portions of the flexible boot relative to the outer ring or the inner ring axle for the intended purposes, the metal hoop must be fastened under a predetermined interference. However, considering the functionality of the constant velocity universal joint, the constant velocity universal joint must have a working angle on an outboard side, which is greater than that on an inboard side and, accordingly, leakage of the grease tends to occur at the outboard joint where the annular anchoring portion of the boot is fixed to the outer ring of the constant velocity universal joint.
In view of the above, the JP Laid-open Patent Publication No. 07-145863, for example, suggests fixture of the annular anchoring portion of the boot to the outer ring of the constant velocity universal joint, in which annular protrusions are formed integrally with the anchoring portion of the boot so as to project radially outwardly and inwardly therefrom, respectively, and, on the other hand, a similarly annular groove is formed in an outer peripheral surface of the outer ring. In this known boot fixing method, the annular protrusion projecting radially inwardly from the anchoring portion is engaged in the annular groove defined in the outer ring, and a metal hoop then encircled exteriorly around the anchoring portion is firmly fastened to fix that anchoring portion to the outer ring.
According to the above described boot fixing method, when the metal hoop is so fastened, the annular protrusion projecting radially outwardly from the anchoring portion is radially inwardly compressed by a clamping force exerted by the metal hoop, accompanied by an elastic deformation of the annular protrusion projecting radially inwardly from the anchoring portion to allow the annular protrusion to be urged into the annular groove to thereby achieve a tight connection between the anchoring portion and the outer ring.
It has however been found that the known boot fixing method discussed above has a disadvantage in that since the flexible boot anchoring portion has a complicated shape, the cost of manufacture of the boot tends to increase. Also, considering that the available space is limited on the side of the outer ring of the constant velocity universal joint, formation of the annular protrusion on the outer periphery of the anchoring portion requires a contrived design setup. Furthermore, in the event that a hard matter, such as a stone, collides against the annular protrusion on the outer periphery of the anchoring portion during travel of the automotive vehicle, another problem occurs that the clamping force is so lowered as to impair the sealability.